Where the river meets the sea Two days. Five ways to run the Texas coast. Matagorda is where the Colorado River finally gives up and hands itself to the Gulf. LCRA's Matagorda Bay Nature Park is flat, wide open, and quiet in a way that most of Texas is not. In February the heat is gone, the light is long, and the wind coming off the water is the only hill you will climb all weekend. Saturday belongs to the Backyard Ultra: one loop, one hour, over and over, until one runner is left. Sunday belon…